Bending of boards



April 10, 1945- J. w. JACKSON 2,373,567

BENDING 0F BOARDS Filed Oct. 16, 1942 2 Sheets-Sheet l NIW" April 10,1945 J. w. JACKSON 2,373,567

BENDING OF BOARDS Filed Oct. 16, 1942 2 Sheets-Sheet 2 Patented Apr. 10,194.5y

UNITED STATES PATENT OFFICEK Application October 16, 1942, SerialNo.462,283

` 11 Claims. (Cl. 1411-268) The present improvements relate to thebending of boards, such for example as plastic sheets, plywood,composition boards, etc. A primary object served by. this invention isthe production in such a board of bends which are accurate, de-

pendable, enduring, safe and smooth, by a simple and inexpensiveapparatus, as will be hereinafter described.

A hardbcard usually incorporates in its structure numerous bers whichare susceptible to breaking or splitting if the board be bent through arelatively short radius. For this reason aswell as others the bending ofhardboard has generally been considered as presenting special problems.These diiculties commonly arise through the employment of long standingbending practices which have undergone little, if any, changes over aperiod of many years. The application of the usual heavypressureLsuiiicient to force a frictional bending of the material, isoften detrimental in the treatment of composition boards, for example,consequently I prefer to employ an altogether diierent and frictionlessprinciple of operation.

According to the present invention, the board to be bent may be eitherdry or wet. For the bending operation I utilize a roll, circular orotherwise, about which the board is wrapped, the roll being either coldor heated. It is desirable, however, particularly to facilitate andexpedite operations, that the roll be heated and that the board be wet.A point of primary importance is the application of the force whichoperates upon the board to produce the bend. I find it satisfactory toemploy for this purpose a roll having a radius the same as, or veryslightly less than, the bend desired for the board, and then, afterclamping the board to the roll, advance the roll along the board for adistance commensurate with the bend that is desired. In this operationthe roll axis executes a linear movement, and the roll need not bemounted within any bearings, xed or otherwise.

. Boards which are bent in accordance with the ensuing description maybe used for many pur- DOSes, some of which have heretofore been servedregularly by sheet metal. One example is a pipe, requiring va. bend of360 or more. Another example is a reflector for uorescent lights. Twobends, each something less than 90, are usually formed in such areflector, the two regions of bend being separated from each other andfrom the edges of the board. These are two convenient examples of use towhich a bent board may be put. The apparatus herein shown and describedis designed with particular reference to the production of one or morebends in a board which may serve in any such capacity.

In the drawings:

Figure 1 is a central sectional view through the machine, lengthwisethereof, showing the bending roll in its initial position of rest;

Fig. 2, which is a similar View, shows the bending roll in its inalposition wherein a bend has been imparted to the board;

Fig. 3 is an enlarged detail in section taken on line 3 3 of Fig. 1;

Fig. 4 is an end elevation of al bending roll equipped with amodification in the weight mechanism;

Fig. 5 is .a top plan view of the machine as shown in Figs. 1 and 2;

Fig. 6, which is a. view similar to Fig. 3, shows a modification in theclamping bar;

Fig. 7 is a View generally similar to Fig. 1 wherein the machine isshown as vertically rather than horizontally disposed;

Fig. 8 is a view, partly in elevation and partly in section, of a duplexmachine in which two bends may be produced simultaneously; and

Fig. 9 is a transverse sectional view of a ma- A chine of modifiedconstruction.

In employing the present apparatus, for 'bending of composition boards,known generally as hardboard it may be desirable, although notnecessary, to first wet the board as with water, oils, thermo-settingsynthetic resins, or other softening or reactive agents.While'performing a bend, I am careful not to force the board. Instead itis subjected to a frictionless pressure, constantly and perhaps variablyapplied, and exerting always a persuasive force, tending to bend theboard at a rate which varies with the willingness of the board itself,at each successive point, throughout the region where bending takesplace. A bend so performed may proceed relatively slow or fast, and alsoat variable speeds, depending upon the willingness of the board at eachpoint which is subjected to the bending strain, and because of thispeculiar relationship between the applied force and the boardresistance, breaking, splitting or rupturing of the board in the regionof its bend is avoided.

In the machine shown in Figs. l-3 and 5, I employ a horizontal tablewhose top T provides a heat-resistant support whereon a board B may befreely rested. lNear the edges of this table top are placed a pair ofspaced stops Il) adjustable vertically or horizontally of the table inwhose top may be formed, in one end region thereof, a

crosswise recess for receiving in ush relation a pair of anges IIextending horizontally from two depending angle plates with anelectrical heating element l2 therebetween. Heat conducted to the angesis thereby transmitted to the overlying board B in its end region wherebending is to take place.

Upon a. table so constructed is placed a bending roll R which may be apipe or tube having a radius approximately the same as that desired forthe bend to be imparted to a board. The roll whose axis is movable ispositioned with its axis crosswise of the table, the roll ends beingdesirably extended beyond the sides thereof (see Fig. 5). In its initialposition the roll abuts a pair of blocks I4, as shown. A clamp C, hereshown as an angle bar, is tted to the roll lengthwise thereof, beingsecuredV thereto near opposite ends thereof with bolts l5, arranged inpairs, the bolts passing through spacer plates I6, affixed to the rolladjacent the ends thereof, whereby the clamp is maintained in a fixedspaced-apart relation to the roll a distance somewhat greater than thethickness of the board which is to be operated upon (see Fig. 3). Alsocai'ried by the clamp is a pair of gauges I1, each adjustable in adirection lengthwise of the table (when the roll is in the initialposition of Fig. 1), and formed with an upturned finger I8 against whichthe board may abut when advanced into operating position in the spacebeneath the roll and above the clamp.

By shifting these gauges to move the fingers toward or from the tablethe board may be accurately positionedto receive a bend which startsclose toits end, or at a distance which is removed therefrom, the arc orextent of the bend being determined by the distance through which theroll is thereafter permitted to advance before the stops l 0 areengaged.

It is often desirable that the roll be heated, a suggestive means forthis purpose being the pipe 20 that is axially mounted within the roll,the pipe walls being formed with numerous radial ,openings through whichgas may escape to be burned in the form of flame jets which will impartheat to the surrounding roll. A flexible connection 2| (see Fig. 4)leads from a gas supply to the pipe for delivering fuel thereinto. Toutilize gravity force for advancing the roll I may employ any one ofseveral expedients one of which, shown in Figs. 1-3 and 5. comprises apair of co-planar rods 22 extending radially from the roll and rotatablerelative thereto. each rod supporting an off-center weight 23 adjustablelengthwise thereof. The direction in which these rods are extended ispreferably vertically upwardly when the roll is in its initial positionof rest (see Fig. 1) wherein the clamp C engages the tops of a. pair ofvertically adjustable swinging links 24. Each link 24 is pivoted at oneend on a bolt 24 and on its opposite end carries a bolt 24a which hasmovement in the respective arcuate slot 24b and tightened in the slot bymeans of the respective nut 24c whereby to adjustably support the clampC at one end of the table T. In the position illustrated, thepreponderance of weight will be to the left of the roll axis, tending tohold it at rest. but when tle rods are turned around to oppositepositions (see Figs. 2 and 5) the roll will tend to advance to the rightin response to the gravity force exerted by the Weight preponderance tothat side of the roll. The amount of the force so exerted may becontrolled within wide limits by the adjusted radial positions of theweights relative to the roll. .An alternative de- 75 vice for utilizinggravity force is also suggested in Fig. 4 wherein the roll R is fittedat its ends with ilanged wheels 25 to each of which is fastened andextended therearound a flexible cord 26 which carries at its dependingend a. weight 21. The roll in this case is also shown as mounting a pairof balanced .weights 28 whereby to increase the pressure with which itbears on the board undergoing treatment. These two expedients ofutilizing gravity force for advancing the roll lengthwise of the boardand for increasing its pressure thereupon are suggestive of many whichare available.

In operation, a board is slipped into place while the roll is in itsinitial position where the vertical flange of the angle clamp is restednear opposite ends upon the vertically adjustable supporting plates 24so that the roll will be maintained at the desired elevation. The boardend then lies bet-Ween the roll bottom and the clamp therebelow so as toheld thereby against the roll during advance thereof along the boardlengthwise thereof. The weights employed for utilization of gravityforce are suflicient to produce a slow persuasive movement of the rollagainst the yielding resistance offered by the board. During thismovement the board wraps itself around the roll without friction to theextent 0f the roll advance which ceases when engagement with the stopsensues. In the form shown in Figs. l and 5 these stops lie in the pathof the roll to be engaged thereby WhereasY in the showing of Fig. 2 thestops are supported in the path of the radius rods 22 to receiveengagement therefrom. The bend thus imparted to the board will extendthrough the arc determined by linear advance of the roll, the region ofthe bend being iixed by adjustment of the gauges which determine thestarting point, of the bend. Several minutes may elapse between thestart and nish of this operation, the roll advancing slowly lengthwiseof the board, and perhaps at a rate of speed which is variable dependingupon the yielding resistance that is offered by the board.

The clamp which serves to hold the board against the roll may optionallybe constructed as per Fig. 6 Where it is shown as a bar 30 removablysecured at one end to a hook plate 3l which is affixed to the roll R,the opposite bar end being provided with a keeper 32 which extendstransversely through registering openings in a spacer plate 33 and thewall of the roll to be engaged by a bolt 34 normally urged to lockingposition by a spring 35. This bolt may be supported in a block 36 thatis aflixed to the inner face of the wall of the roll adjacent one endthereof so as to be convenient for manipulation. In practice theclamping bar which is thus removably carried by the roll may readily bedetached therefrom when convenience will be served as, for example, whena board With an extended bend, or with a bend removed from its ends, isto be stripped from the machine.

Referring now to Fig. 7, I have here shown a very similar constructionin which the board support T is vertical, beingV carried by a framewhich comprises a vertical post 40 defining with the support a guidewayin which the roll R is free to move through a vertical path. This rollis equipped with a suitable clamping bar C for engaging with the board Bwhereby to hold it against the roll during its descending movement inresponse to a requisite force, gravity or other# wise. The roll in thisVconstruction may be heated, as by gas delivered through a burner pipe2U the same as already described, and in operation will perform the sameas the rolls of Figs. 1-5.

A duplex machine for making two bends simultaneously in either the sameboard or in two different boards, is illustrated in Fig. 8. The partsemployed in such a duplex machine may be the same as those alreadydescribed and so bear corresponding reference characters, but they areto some extent duplicated so as to have capacity for operating upon twospaced-apart regions of the same board or upon two separate boards whichare arranged edge to edge. It is necessary only to note that the tworolls advance toward each other to the limits which are determined bythe stops, and that during the advance of each a bend is produced in theengaged board to the extent that it is wrapped around the roll.

A weight 23 carried on a radial rod 22 will obviously exert anincreasing torque force on the roll through the first 90 of its advance.'I'his'is desirable both because most commercial bends are less than 90and because theapplication of a progressively increasing force isconducive to safest results. At the start the board willingness to yieldis not so great as later, due probably to the fact that bending strainstransmitted ahead to points of the board later to be bent will conditionthe board at such points for more ready yielding when finally subjectedto the bending force imparted by the roll.

In Fig. 9 I have illustrated a bending roll R supported upon rollers 40for rotation upon a fixed axis. A spring-pressed guide roller 4Iadjacent the bending roll holds a board B tangentially thereagainst, itsleading edge being secured by a clamp C which is carried by the bendingroll. When relative movement takes place between the board and bendingroll, produced either by applying a. torque force to the roll or athrust force to the board, or both, the board will undergo africtionless bend in the manner already set forth.

From the foregoing description, it will be noted that bending of a boardinvolves (1)-tangential securement of the board to a bending roll, and(2) relative motion between the board and roll, in response to a gravityor equivalent force, such as to produce a wrapping of the board aroundthe roll to the arcuate extent of the desired bend. Such a bend, whencompletedin a hardboard. will be permanent, and for ready stripping ofthe board only a reverse relative movement between the board and rollis-require'd.

I claim:

1. In a board-bending machine, means providing for the board a supportagainst which the board may be rested,a bending roll advanceable alongthe board in engagement with one surface thereof, means connecting oneedge of the board to the roll in parallelism with the axis thereof andadapted to hold the board closely against the roll during all stages ofadvance thereof, said connecting means initially constituting asupportportion in alignment with the said board support and movable out ofalignment therewith as the bending roll advances along the board, andstop means for limiting advance of the roll through a fixed distanceduring which the board is Wrapped around upon the roll surface inconformity therewith and through an arc commensurate with its distanceof advance.

2. In a board-bending machine, means providing for the board a supportagainst which the board may be rested, a bending roll movably mountedabove the board and advanceable along the board in full weightengagement with the upper surface thereof, a weight movably mounted uponthe roll adapted in one position to dispose a preponderance of gravityforce to one side of its axis and in an opposite position to dispose avpreponderance of gravity force to the opposite side of its axis, meanscarried by the roll and engageable with the board to hold it closelyagainst the roll during all stages of advance thereof, and stop meansfor limiting advance of the roll through a fixed distance during whichthe board is wrapped around upon the roll surface in conformitytherewith and through an arc commensurate with its distance of advance.

3. In a board-bending machine, means providing for the board a supportagainst which the board may be rested, a bending roll advanceable alongthe board in engagement with one surface thereof, a combined board gaugeand clamp affixed to the roll for positioning and holding the boardclosely against the roll during all stages of advance thereof, saidcombined board gauge and clamp normally lying in abutting relation toand in the horizontal plane of the board support and movable upwardlyout of said plane as the roll advances along the board, and stop meansfor limiting advance of the roll through a xed distance during which'theboard is wrapped around upon the roll surface in conformity therewithand through an arc commensurate with its distance of advance.

4. In a board-bending machine, means providing for/the board a supportagainst which the board may be rested, a bending roll advanceable alongthe board in engagement with one surface thereof, means removablycarried by the roll env gageable with the board and constituting anextension of the board support and adapted with the yrotation of theroll to closely hold the board against the rollduring all stages ofadvance thereof and, upon removal, permitting free release of the board,and stop means for limiting advance of the roll through a fixed distanceduring which the board is wrapped around upon the roll surface inconformity therewith and through an arc commensurate with its distanceof advance.

5. In a board-bending machine, a support together with a roll proximatethereto, the two being adapted to receive therebetween the board to bebent, a weight carried by the roll adapted in one position to dispose apreponderance of gravity force to one side of its axis and in anopposite position to dispose a preponderance of gravity force to theopposite side of its axis, and means carried by the roll engageable withthe board at one end of the latter for holding the board tangentially atone linear point closely against the roll throughout the cycle ofmovement.

6. In a board-bending machine, a support together with a roll proximatethereto, the two being adapted to receive therebetween the board to bebent and to provide for relative movement between the roll and board,means carried by the rollengageable with the board at one end of thelatter for holding the board tangentially at one linear point closelyagainst the roll throughout the cycle of movement, and means adjustablein a direction substantially radially of the roll when in its initialposition affording therefor a support at a desired point relative to theplane of the board.

7. In aboard-bending machine, means providing for the board a supportagainst which the board may be rested, a bending roll mounted to rollalong the board, clamping means secured to the roll and having a portiondisposed normally in the plane of said supporting means to freelyreceive an edge of the board between the supporting means and theclamping means, and means whereby to advance the roll over and on theexposed face of the board and simultaneously shift said clamping meansout of the plane of said supporting means in clamping relation with theroll to bind the board tightly between the clamping means and roll tobend the board.

8. In a board-bending machine including a movable roll and means wherebythe said roll may be moved to bend the board, a clamping elementsubstantially coextensive with the length of the roll and nxedly securedthereto adjacent each end of the roll and between its points ofconnection with the ends of the roll providing a space for the insertionof the board between the roll and the clamping element, said spacebetween the roll and clamping element being substantially coextensivewith the length of the roll whereby the end of the board to be bent isfreely inserted into said space and projected beyond the said vclampingelement, whereby upon movement of said roll the board is bent to conformto the shape of that portion of the roll that it engages during movementof the roll.

9. In a board-bending machine, means providing for the board a. supportagainstY which the board may be rested, a bending roll mounted to moveon the board and advanceable along the board in full weight engagementwith one sur face thereof, a combined board guage and clamp secured tothe roll with the clamp normally in abutting relation with one end ofsaid supporting means and with the clamp spaced slightly from the rollto provide a space for the free insertion of the board between the rolland clamp into engagement beyond the clamp with the outer end. of theguage, means whereby to move the roll and simultaneously shift the guageand clamp away from abutting relation with the supporting means so as tobend the board on the roll during all stages of advance movement of theroll, and means for limiting the advance movement of the roll.

10. In a board-bending machine, means providing for the board a supportagainst which the board may be rested, means carried by the supportingmeans for heating the board mounted on the supporting means, a bendingroll rotatively mounted to rotate on the exposed surface of the boardand advanceable along the board in engagement with the exposed surfacethereof, a combined guage and clamp secured to the roll with a portionof the clamp being substantially coextensive with the length of the rolland spaced slightly therefrom to provide a space to freely receive oneedge ofthe board, the board being positioned between the roll and theclamp and having one edge in engagement with the outer end of the guage,a portion of the clamp forming an extension of said board supportingmeans and separable therefrom, means whereby to rotatively advance theroll along the board and simultaneously shift the clamp and guage awayfrom the board supporting means and wrap the board around the roll tobend the same, and means for limiting rotative movement of the roll.

l1. In a board-bending machine, a supporting means for the board, abending roll advanceable along the board in engagement with one surfacethereof, and means to connect one edge of the board to the roll inparallelism with the axis thereof, including a combined clamping memberand gauge secured to the roll, the gauge extending laterally from theclamping member beyond the roll and disposed normally in horizontalalignment with said supporting means and movable out of alignmentwiththe latter in the rear of the roll as the roll advances along thesurface of the board. j

J. WILLIS JACKSON.

